A short message, as a convenient and fast contact way, enjoys the popularity of more and more users in recent years and makes a rapid progress. But the same as an email, a mobile phone short message is increasingly troubled by a lot of spam messages. At present, there are more than 600 million mobile phone users in China, with up to 800 million short messages sent every day and 8 spam messages received by every user every week on an average. For a mobile user, a spam message not only seriously influences a normal life of the user but also harms the individual privacy; for operators, the overflow of spam messages causes a huge investment waste to the infrastructure, such as a short message center, and increases the danger of a network suffering from a malicious attack; therefore, the parties concerned are hustling to set up related laws and regulations, the operators also pay more and more attentions to spam messages and build spam message filtering systems to filter spam messages by technical means so as to create a continuous, sequential and healthy development environment for the development of a short message service (SMS).
Generally, the spam message filtering system filters messages in terms of such aspects as short message content, short message flow and user numbers; one of the basic filtering measures is to filter a short message by matching key words of short message content, for example, the short message content containing key words involving pornography, retroaction and other definitions can be directly filtered out by matching key words. At present, among short messages sent by users, a number of the short messages are long short-messages, wherein the long short-message is a short message with a character number exceeding a certain number (generally exceeding 70 Chinese characters or 160 English characters); the long short-message often may be split into multiple short messages when being sent. After the long short-message is split, the key words defined by the spam message filtering system may be partitioned into multiple short messages, however, the present spam message filtering system processes the long short-message by filtering the split messages respectively, therefore, the message content of the long short-message whose split part contains the key words can not be effectively filtered out.